I have a netbook which has from time to time "issues", which makes me have to hard power it down. The video card driver is experimental (xf86-video-intel29) still doesn't have GEM support that I know, and the computer completely locks up if ever i have hw.acpi.lid_switch_state set to anything but NONE. More recently the screen will go blank and not come back without a reboot.

ACER Aspire One (ironically the web cam works with pwc view hehe)

What i'm asking is, if there is any way to turn off the auto background fsck'ing that's done if ever the computer booted up but i had to hard power it down. I would like to be able to manually fsck it, at my convenience. Sometimes I have to quickly get something off it and i don't have time to wait for it to fsck.

When an automatic reboot is in progress, rc is invoked with the argumentautoboot. One of the scripts run from /etc/rc.d/ is /etc/rc.d/fsck.
This script runs fsck(8) with option -p and -F to ``preen'' all the disks
of minor inconsistencies resulting from the last system shutdown. If
this fails, then checks/repairs of serious inconsistencies caused by
hardware or software failure will be performed in the background at the
end of the booting process. If autoboot is not set, when going from sin-
gle-user to multi-user mode for example, the script does not do anything.

Now that you know what you can edit to prevent fsck from running, I recommend strongly that you DON'T DO IT. If there are filesystem inconsistencies, and you change anything in the filesystem, you risk altering the integrity of the filesystem and losing part or all of it.

Mount inconsistent filesystems read-only, if you must access data quickly and you cannot wait for fsck to complete its work. Writing on them in that state would be a poor operational decision.